- Epidiolex® (cannabidiol) oral solution approved by FDA and on track to be launched in Fall -

- Conference call today at 4:30 p.m. ET -

London, UK, Carlsbad, CA, 7 August 2018: GW Pharmaceuticals plc (NASDAQ: GWPH, GW, the Company or the Group), the world leader in the development and commercialization of cannabinoid prescription medicines, announces financial results for the third quarter ended 30 June 2018.

§ Key favorable patent grants by USPTO related to the use of CBD in epilepsy, including claims for the treatment of relevant seizure types associated with LGS and Dravet syndrome, as well as the use of CBD with clobazam

· Patents align directly with new Epidiolex FDA label and to be listed in Orange Book

· Patent expiry dates to 2035

§ Additional patent applications under review and being filed as new data is generated

· Cash and cash equivalents at 30 June 2018 of £334.0 million ($440.2 million) compared to £241.2 million as at 30 September 2017

· Revenue for the nine months ended 30 June 2018 of £10.7 million ($14.2 million) compared to £6.1 million for the nine months ended 30 June 2017

· Loss for the nine months ended 30 June 2018 of £136.7 million ($180.2 million) compared to £90.3 million for the nine months ended 30 June 2017

Solely for the convenience of the reader, the above balances have been translated into U.S. dollars at the rate on 30 June 2018 of $1.31792 to £1. These translations should not be considered representations that any such amounts have been, could have been or could be converted into U.S. dollars at that or any other exchange rate as at that or any other date.

Conference Call and Webcast Information

GW Pharmaceuticals will host a conference call and webcast to discuss the third quarter 2018 financial results today at 4:30 pm EST. To participate in the conference call, please dial 877-407-8133 (toll free from the U.S. and Canada) or 201-689-8040 (international). Investors may also access a live audio webcast of the call via the investor relations section of the Company’s website at http://www.gwpharm.com. A replay of the call will also be available through the GW website shortly after the call and will remain available for 90 days. Replay Numbers: (toll free):1-877-481-4010 or 919-882-2331 (international). For both dial-in numbers please use conference Replay ID: 35897.

About GW Pharmaceuticals plc and Greenwich Biosciences, Inc.

Founded in 1998, GW is the world leader in the development and commercialization of cannabinoid prescription medicines. The Company’s lead product, EPIDIOLEX® (cannabidiol) oral solution, received U.S. FDA approval in June 2018 and is under review by European regulators. Previously, GW commercialized the world’s first plant-derived cannabinoid prescription drug, Sativex® (nabiximols) in Europe and is now advancing plans to develop this medicine in the US. The Company has a deep pipeline of additional cannabinoid product candidates which includes compounds in development for epilepsy, autism, glioblastoma, and schizophrenia. For further information, please visit www.gwpharm.com.

Forward-looking statements

This news release contains forward-looking statements that reflect GW's current expectations regarding future events, including statements regarding financial performance, the timing of clinical trials, the timing and outcomes of regulatory or intellectual property decisions, the relevance of GW products commercially available and in development, the clinical benefits of EPIDIOLEX (cannabidiol) oral solution and the safety profile and commercial potential of EPIDIOLEX. Forward-looking statements involve risks and uncertainties. Actual events could differ materially from those projected herein and depend on a number of factors, including (inter alia), the success of GW’s research strategies, the applicability of the discoveries made therein, the successful and timely completion and uncertainties related to the regulatory process, and the acceptance of Sativex, EPIDIOLEX and other products by consumer and medical professionals. A further list and description of risks and uncertainties associated with an investment in GW can be found in GW’s filings with the U.S. Securities and Exchange Commission, including the most recent Form 20-F filed on 4 December 2017. Existing and prospective investors are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. GW undertakes no obligation to update or revise the information contained in this press release, whether as a result of new information, future events or circumstances or otherwise.

Enquiries:

GW Pharmaceuticals plc

Stephen Schultz, VP Investor Relations (U.S.)

917 280 2424 / 401 500 6570

U.S. Media Enquiries:

Sam Brown Inc. Healthcare Communications

Christy Curran

Mike Beyer

615 414 8668

312 961 2502

EU Media Enquiries:

FTI Consulting

Ben Atwell

Simon Conway

+44 (0) 3727 1000

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